Process for producing a planar dimmer

ABSTRACT

A process for producing planar dimmer comprising a transparent base, a dimming part, capable of dimming, disposed on the base, the dimming part comprising a first electrode layer formed on the base, a second electrode layer set facing the first electrode layer, a coloring part, disposed between the two electrode layers, and colors or discolors in response to the stimulus from the two electrode layers, and a conducting part disposed between the base and the first electrode layer in such a way as to be in contact with the first electrode layer in order to apply a uniform voltage throughout the first electrode layer. 
     The process includes forming paint stripes, electrolessly plating a metal film over each of the stripes, forming an electrode layer over the metallized stripes, and forming a color-forming layer over the electrode layer.

This is a division of application Ser. No. 07/173,594, filed Mar. 25,1988.

FIELD OF THE INVENTION

The present invention relates to electrochromic elements used in varioustypes of displays and planar dimmers, and specifically to planar dimmersusing electrochromic elements with large areas.

DESCRIPTION OF THE RELATED ART

An electrochromic element, comprising an oxidative color-forming layerand a reductive color-forming layer inserted between a pair ofelectrodes, is an element that is capable of coloring and discoloring asa result of electrochemical redox reaction.

One type of planar dimmer using this electrochromic element is shown inFIG. 10(a) and FIG. 10(b), known as the all-solid type. This has atransparent base 41 and on top of it, consecutively piled together, atransparent electrode 42, a color-forming layer 43, an electrolyte 44, acolor-forming layer 45, and another electrode 46, with parts 47a, 47b onthe electrodes 46, 42 respectively for connecting lead wires. Thisdevice is of the type where a pair of bases 41 are piled consecutively,on top of one another. One of the bases has a transparent electrode 42and an oxidative color-forming layer 43 thereon, and the other atransparent electrode 42 and a reductive color-forming layer 45 thereon.These bases are prepared and, between the color-forming layers anelectrolyte 44, which can be either a solution, a gel or a solid, isinserted.

In planar dimmers where this type of electrochromic element was used,when the area of the electrochromic element was large, on coloring ordiscoloring, a problem arose with regard to the responses of theoxidative color-forming layer 43 and the reductive color-forming layer45. In other words, because the plate resistances of the transparentelectrodes 42, 46 are high, when voltage was applied, coloring ordiscoloring did not occur quickly and evenly throughout theelectrochromic element. Coloring or discoloring occured gradually,starting from the part where the voltage was applied. This kind ofcoloring or discoloring process of the color-forming layers was notconsidered impressive or acceptable.

Besides, in the planar dimmer using the electrochromic element mentionedabove, when the area of the element is large, due to an excessive amountof current being supplied to the area near the lead wire connectors 47a,47b along the circumference of the transparent electrodes 42, 46, theseparts near the lead wire connectors 47a, 47b easily deteriorate.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a planar dimmer thathas excellent dimming qualities and can color and discolor throughout,quickly and evenly.

One other objective of the present invention is to provide a planardimmer whose clarity or visibility is not impaired.

One other objective of the present invention is to provide a planardimmer with a long lifetime, where there is no excessive supply ofcurrent along the circumference of the electrode layers.

One other objective of the present invention is to provide a method ofmanufacturing a planar dimmer wherein the electroless plating methodemployed in forming a metal film can be effectively performed.

A further objective of the present invention is to provide a planardimmer with improved durability as a result of strengthening theadhesiveness of the electrode layer to the base.

In order to realize the objectives mentioned above, the presentinvention comprises a transparent base, a dimming means, capable ofdimming, disposed on top of the base, the dimming means comprising afirst electrode layer disposed on top of the base, a second electrodelayer set facing the first electrode layer, and a coloring means, whichcolors or discolors in response to the stimulus from the electrodelayers, disposed between these two electrode layers, and a conductingmeans, located between the base and the first electrode layer, disposedin such a way as to be in contact with the first electrode layer so thata uniform voltage is applied throughout the first electrode layer.

Other objectives of the present invention will become apparent with anunderstanding of the embodiments described later and the appendedclaims. Further, many advantages not mentioned in this specificationwill become obvious to one skilled in the art upon application of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 and FIG. 2 show a first embodiment of the present invention;

FIG. 1 is a partial horizontal sectional view of a planar dimmer usingan electrochromic element, FIG. 2 is a partially broken plane view of aplanar dimmer,

FIG. 3 is a sectional view showing the electrochromic planar dimmer ofsecond and third embodiments of the present invention,

FIG. 4 is a sectional view showing the paint films after being formed onthe base,

FIG. 5 is a sectional view showing the metal films after being formed onthe paint films,

FIG. 6 is a sectional view showing a transparent electrode layer afterbeing formed over the metal films,

FIG. 7 is a sectional view showing a color-forming layer after beingformed on the transparent electrode layer,

FIG. 8 is a partial horizontal sectional view of the planar dimmer of afourth embodiment,

FIG. 9(a) to FIG. 9(f) show the process of manufacturing theelectrochromic base, and

FIG. 10(a) and FIG. 10(b) show sectional views of related art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A detailed description of the first embodiment of the planar dimmer,using an electrochromic element, of the present invention will be givenhereafter with reference to FIG. 1 and FIG. 2.

As shown in FIG. 1, the planar dimmer comprises a pair of transparentbases 2, 3 made of polycarbonate and an electrochromic element 4, whichmakes up the dimming means, connectedly disposed between the twotransparent bases 2, 3.

The electrochromic element 4 comprises a pair of transparent electrodelayers 5, 6, an oxidative color-forming layer 7 and a reductivecolor-forming layer 8 as color-forming layers disposed between the pairof transparent electrode layers 5, 6, and an electrolyte 9 disposedbetween the color-forming layers 7, 8. The color means is made up of thetwo color-forming layers 7, 8 and the electrolyte 9. Further, a sealingmaterial 10 made of resin is set between the transparent electrodelayers 5, 6 along the side edges of the planar dimmer. One end of thelead wires 11a, 11b is connected to the transparent electrode layers 5,6 by solders 12, on the parts in contact with the sealing material 10.

As shown in FIG. 1 and FIG. 2, a plurality of fine and long conductors13, 14 (22 μm in diameter in this embodiment), making up the conductingmeans, with conductance better than that of the transparent electrodelayers 5, 6, are arranged, parallel to each other, at equal intervals (1mm in this embodiment) on the inner surface of the transparent bases 2,3. A portion of each conductor 13, 14 is embedded in the transparentbases 2, 3 and further connected to the transparent electrode layers 5,6. Both ends of each conductor 13, 14 are respectively electricallyconnected to the lead wires 11a and 11b. In this embodiment, a productof Shinetsu Polymer Co., Ltd. with the trade name POLYTECH PANEL M,which has the conductors 13, 14 already embedded in the transparentbases 2, 3, is used.

Thus, when voltage is applied on the transparent electrode layers 5, 6and on the conductors 13, 14 via the lead wires 11a, 11b, the resistanceis decreased due to the low resistances of the conductors 13, 14 and auniform voltage is applied throughout the transparent electrodes 5, 6.Consequently, a quick redox reaction is induced between the oxidativecolor-forming layer 7 and the reductive color-forming layer 8, bothcolor-forming layers, as a whole, exhibiting a rapid coloring response.As a result, the electrochromic element 4 itself exhibits quick anduniform coloring.

Further, when a voltage with reversed polarity is applied, anapproximately uniform reverse voltage is applied throughout thetransparent electrode layers 5, 6 through the conductors 13, 14 and thecolor-forming layers 7, 8, as a whole, exhibit a rapid discoloringresponse. As a result, the electrochromic element 4 itself quicklybecomes transparent. In this embodiment, fine 22 μm conductors are usedand, since they almost have no effect on visibility and transmittancy, aplanar dimmer with excellent dimming qualities can be realized.

The present embodiment is not limited to the structure described above.For example, a plate made of transparent resin such as acrylic resin,polyester resin and others or an inorganic plate glass can be used forthe base 2, 3. The conductors 13 on the transparent electrode layer 5and the conductors 14 on the transparent electrode layer 6 can bearranged perpendicular to each other, or one of the transparentelectrode layers 5, 6 can be an electrode made of aluminum, and others.Without departing from the spirit of the present invention, in itsapplication, a part of its structure can be changed appropriately.

Further, since there is no impairment of visibility owing to the use offine conductors, the present invention can also be used as anelectrochromic element for displays. Moreover, iron wires, which has theeffect of reinforcing the plate glass or the resin plate or preventingthem from scattering when breaking, can also be used as conductors.

A second embodiment of the present invention will be described belowwith reference to FIG. 3 to FIG. 7.

As shown in FIG. 3, in the electrochromic planar dimmer of thisembodiment, bands of paint films 22 and metal films 23 are formed atfixed intervals on the two transparent bases 21 made of glass.Transparent electrode layers 24, 30 and an oxidative color-forming layer25 or a reductive color-forming layer 29 are formed on both bases 21.Further, an electrolyte 28 is formed between the two color-forminglayers 25, 29. Both color-forming layers 25, 29 and the electrolyte 28make up the coloring means. Both ends of the electrolyte 28 are sealedwith resin 27. The electrochromic element 26, comprising the transparentelectrode layers 24, 30, the color-forming layers 25, 29, theelectrolyte 28 and the resin 27, makes up the dimming means.

Plate glass or transparent heat resistant resin such as polyethersulfon, polyether ether ketone and others are used for the bases 21mentioned above.

The paint films 22 mentioned above are formed according to the followingprocedure.

First, the surfaces of the bases 21 are washed with solvents such asmethanol, ethanol, isopropanol and others. Then, an epoxy resin paint(bisphenol A type epoxy resin paint) mixed with palladium (Pd) andcopper (Cu) is applied, by common screen printing, throughout the bases21 in 1 mm wide long strips at equal intervals of 10 mm.

Next, the epoxy resin paint is made to harden by heating the bases 21 toabout 150° to 200° C. for about thirty minutes. Then, the bases 21 areimmersed in acid. For example, the bases 21 are immersed for two minutesin a 35° C., 100 ml/l aqueous solution of concentrated hydrochloricacid. Subsequently, the bases 21 are washed with water and the paintfilms 22 are formed on the bases 21 as shown in FIG. 4. Since the Pd andCu mixed with the epoxy resin paint are deposited on the surface of thepaint films 22, these same Pd and Cu will act as catalysts in thefollowing process of electroless plating.

The metal films 23 are formed on the paint films 22 by an electrolessplating method (chemical plating) described next.

Electroless plating is done by immersing the bases 21, with the paintfilms 22 formed on them, for five to seven minutes in a 40° C. nickel(Ni)-phosphorus (P) solution as described below.

    ______________________________________                                        nickel          7 ± 1    g/l                                               sodium hypophosphite                                                                          16 ± 4   g/l                                               sodium phosphite                                                                              120         g/l or less                                       ______________________________________                                    

A product of Okuno Chemical Industries Co. Ltd., with the trade name TMPElectroless Nickel, is used for the electroless plating solutionmentioned above.

Further, after the electroless plating method mentioned above isperformed, electroplating can be performed, as desired, on the paintfilms 22 to improve the conductivity. Electroplating is done using metalplating materials such as nickel (Ni), copper (Cu) and others under thefollowing conditions.

    ______________________________________                                        (1)  Nickel plating                                                                Components of the plating liquid:                                             nickel sulfate       250 to 350 g/l                                           nickel chloride      35 to 50   g/l                                           boric acid           40 to 50   g/l                                           additive             0.5 to 1.0 ml/l                                          Temperature: 55° C., pH: 4.0,                                          Plating time: 25 to 30 minutes, Current density:                              3 to 4 A/dm.sup.2, Thickness of                                               layer: 10 μm                                                          (2)  Copper plating                                                                Components of the plating liquid:                                             copper sulfate       200 to 230 g/l                                           sulfuric acid        50 to 70   g/l                                           chlorine ions        40 ± 10 ppm                                           additive             3 to 5     ml/l                                     ______________________________________                                         Temperature: 22° C., Plating time: 25 to 30 minutes,                   Current density: 3 to 4 A/dm.sup.2, Thickness of layer: 10 μm         

As shown in FIG. 5, the metal films 23, that make up the conductingmeans, are formed on the paint films 22 as described above.

Next, as shown in FIG. 6, transparent electrode layers 24 about 2000 Åthick are formed on the bases 21, by ion plating method, etc., over thepreviously formed paint films 22 and metal films 23.

Further, as shown in FIG. 7, on one of the bases 21, an oxidativecolor-forming layer about 4000 Å thick is formed by the electrolyticpolymerization of color-forming layers such as polyaniline, polypyrrole,polythiophene and others. Also, in the same manner, on the other base21, a layer of WO₃ 6000 Å thick is formed by EB evaporation method. Thetwo color-forming layers are set facing each other and between them anelectrolyte is inserted, thus forming the electrochromic planar dimmer.

In the electrochromic planar dimmer of the embodiment formed asdescribed above, the metal films 23 take the role of the lead wires,consequently the resistance is decreased, and as the conductionthroughout the transparent electrode layer 24 occurs quickly and evenly,the planar dimmer as a whole colors or discolors evenly and the coloringresponse is rapid as well. Further, since an excessive amount of currentis not supplied along the circumference of the transparent electrodelayer 24, the life of the planar dimmer is longer compared to that whichis not provided with metal films 23.

Next, the third embodiment is described.

The electrochromic planar dimmer of the third embodiment is similar tothat of the second embodiment except for a different material for thepaint films 22 and a transparent polycarbonate resin being used for thebases 21.

The paint films 22 are described next.

A component of the material used in forming the paint films 22 is anetching paint, to be etched after hardening, specifically, acrylic paintthat hardens through exposure to ultraviolet radiation which is anacrylic resin that hardens through exposure to ultraviolet radiationadded with rubber (for example, a product manufactured by Jujo ChemicalCo., Ltd.). The materials used for the acrylic resin that hardensthrough exposure to ultraviolet radiation are denatured polyesteracrylic resin, denatured epoxy acrylic resin and others.

First, by a screen printing method, the acrylic paint that hardensthrough exposure to ultraviolet radiation is applied on the bases 21 ina pattern similar to that of the second embodiment. Next, the paint ismade to harden by exposure to ultraviolet radiation. The process ofhardening the paint by ultraviolet radiation is done in the followingmanner. The bases 21 are bathed in ultraviolet radiation from a 120 W/cmhigh pressure mercury lamp while moving on a conveyor at a speed of 4 to6 m/min.

Next, the hardened paint films 22 are etched. Etching is done byimmersing the bases 21, for five minutes, in an etching solutioncontaining 400 g/l of chromic acid anhydride and 380 g/l of concentratedsulfuric acid heated to 55° to 60° C. Afterwards, the bases 21 arewashed with water.

Subsequently, immersion in acid is performed to denature the paintcausing the pH to increase (toward neutralization). In this case, thebases 21 are immersed for thirty seconds in a 25° C., 100 ml/lconcentrated hydrochloric acid aqueous solution. After the bases 21 arewashed with water, a process of supplying the paint with catalysts isperformed. This process of supplying the catalysts is done by immersionfor ten minutes in a 40° C. liquid mixture of 80 ml/l solution ofpalladium chloride and stannous chloride as main components (an OkunoChemical Industries Co., Ltd. product trade named A-30 Catalyst), and150 ml/l concentrated hydrochloric acid. Afterwards, washing with wateris performed. Finally, acid immersion is done by immersion for twominutes in a 35° C. aqueous solution of 100 ml/l concentratedhydrochloric acid.

Thus, the paint films 22, as shown in FIG. 4, are formed through theprocess described above. The rubber component of the acrylic paint thathardens through exposure to ultraviolet radiation is oxidized anddissolved, and the surfaces of the paint films 22 become rough andbecome supplied with catalysts as well. Consequently, the next processof electroless plating can be effectively performed.

The electrochromic planar dimmer obtained in this embodiment exhibitsthe same effect and performance as in the second embodiment describedpreviously.

The present embodiment is not limited to the constructions describedabove and it may take the following modifications.

(1) Aside from Ni, the conductive material Cu can be suitably used as aplating material in the electroless plating process.

(2) The electrochromic element can be made by forming a transparentelectrode layer 24 and an oxidative color-forming layer 25 (for example,iridium oxide (IrO_(x))) as in the second and third embodiments, and ontop of this, forming an insulating layer, a reductive color-forminglayer 29 (for example, tungsten oxide (WO₃)) and an electrode layer.

(3) In the third embodiment, polycarbonate is used as a material for thebase. When polymethyl metacrylate (PMMA) is used, in the hardening byultraviolet radiation, the bases 21 are preheated for thirty seconds at60° C. then exposed to ultraviolet rays while moving at a speed of 2m/min. Further, etching is performed by immersion for two minutes in a45° to 50° C. etching liquid similar to that used in the thirdembodiment.

(4) The stripes of metal film 23 formed by electroless plating may bearranged intersecting each other.

(5) Transparent resins such as polyester resin, vinyl chloride resin,polystyrene resin and others can be used for the base 21.

Next, a fourth embodiment of the present invention will be explainedwith reference to FIG. 8 and FIG. 9.

In this embodiment, a hard layer 108, made of acrylic paint that hardensthrough exposure to ultraviolet radiation, and making up the connectingmeans is disposed between the transparent base 104 of polycarbonate andthe transparent electrode layer 105. An end of the lead wires 110a, 110bis connected by solders 111 via the conducting pastes 113 disposed alongthe circumference of the planar dimmer. A major portion of theconductors 112, having the same structure as the conductors 13, 14 inthe first embodiment, is embedded lengthwise in the transparent base114, with the jutting part cut and smoothed flush with the base, and theflat surface 112a being connected to the transparent electrode 105.

The structure of the other parts is the same as that of the firstembodiment, the coloring means comprising an oxidative color-forminglayer 106, a reductive color-forming layer 107, and an electrolyte 103,with the dimming means comprising the coloring means mentioned above, atransparent electrode layer 105 and sealing portion 109. In this way,the electrochromic element 114 is formed.

Next, to briefly describe the process of manufacturing the planar dimmerof the present embodiment with reference to FIG. 9(a) to FIG. 9(f),first, grooves 104a for embedding the conductors 112 are carved on onesurface of the transparent base 104 (FIG. 9(a)), and the conductors 112are embedded in these grooves 104a with a part of them jutting out (FIG.9(b)).

Alternatively, without providing grooves on the transparent base 104,the conductors 112 can be glued to the base 104 with an adhesive and, inthe case of a transparent base 104 made of resin that is plasticized byheating, the conductors 112 can be embedded in the transparent base 104by thermal pressing.

Next, an acrylic paint that hardens through exposure to ultravioletradiation is applied throughout the surface of the transparent electrodelayer 105 embedded with the conductors 112, and a hard layer 108 isformed by exposure to ultraviolet radiation. Rising portions on the hardlayer 108 are formed on the surface 108a of the hard layer 108 along thejutting portions of the conductors 112 (FIG. 9(c)).

The surface 108a of the hard layer 108 is ground and the exposed partsof the conductors 112 are cut to be cut surfaces 112a to make the wholesurface 108a uniform (FIG. 9(d)).

Next, a transparent electrode layer 105 is formed on the hard layer 108(FIG. 9(e)) and, on the transparent electrode layer 105, an oxidativecolor-forming layer 106 or a reductive color-forming layer 107 similarto the color-forming layers 7, 8 of the first embodiment are formed(FIG. 9(f)).

Then, an electrolyte 103, similar to the electrolyte 9 of the firstembodiment, is disposed between the two color-forming layers 106, 107and the planar dimmer is formed.

In this embodiment, in addition to the effects described in the firstembodiment, the following advantages are also gained.

A hard layer 108 made of acrylic paint that hardens through exposure toultraviolet radiation is formed between the transparent base 104provided with conductors 112 and the transparent electrode layer 105.Therefore, since the transparent electrode layer 105 is formed on thetransparent base 104 with the hard layer 108 in between, theadhesiveness of the transparent electrode layer 105 to the transparentbase 104 is strengthened. As a result of the reinforced connectionbetween the transparent electrode layer 105 and the transparent base104, the durability of the planar dimmer is improved.

This embodiment is not limited to the structure described above but canbe realized with the following modifications.

(1) A base made of transparent resin such as acrylic resin, polyesterresin and others can be used for the transparent base.

(2) The conductors 112 can be arranged intersecting each other on thetransparent base 104.

(3) One of the transparent electrode layers 105 can be an electrode madeof aluminum.

(4) Iron wires, which have the capability of reinforcing the plate glassand the resin plate and preventing scattering, can be used asconductors.

(5) Adhesives derived from silicon or thermosetting adhesives can beused for the hard layer.

(6) In the process of manufacturing the planar dimmer, an acrylic paintthat hardens through exposure to ultraviolet radiation is applied on thetransparent base 104, the conductors 112 are set and then exposed toultraviolet radiation. In this case, since the exposure is performedwithout the conductors 112 being coated with the adhesive, grinding ofthe adhesive is not required.

Since it is apparent that the present invention can be realized in awide range of constructions without departing from its essence, therealizations of the present invention are not limited to those stated inthe appended claims.

What is claimed is:
 1. A method of manufacturing a planar dimmercomprising the steps for:applying a thermosetting resin paint mixed withpalladium and copper in long stripes, on a base made of glass or heatresistant transparent resin, hardening said paint by heating, immersingsaid hardened paint in acid, forming metal films on said long stripes byelectroless plating, forming an electrode layer on said base that hassaid long stripes and metal films formed on it, and forming acolor-forming layer on said electrode layer.
 2. A method ofmanufacturing a planar dimmer, as set forth in claim 1, furtherincluding the step for performing electroplating after said electrolessplating.
 3. A method of manufacturing a planar dimmer comprising thesteps for:applying an acrylic paint that hardens through exposure toultraviolet radiation, which comprises an acrylic resin that hardensthrough exposure to ultraviolet radiation and rubber components, in theform of long stripes on a base made of any one of polycarbonate andpolymethyl metacrylate, hardening said paint by exposing said base toultraviolet radiation while moving at a fixed speed, etching the base,denaturing said paint to a higher pH by immersion in acid, supplyingcatalysts to said paint, reimmersing said paint in acid after havingbeen supplied with catalysts, forming metal films on said long stripesby electroless plating, forming an electrode layer on said base afterhaving said long stripes and metal films formed on it, and forming acolor-forming layer on said electrode layer.